As is well known to those skilled in the art, hydrocarbon fuels such as aviation jet fuels are expensive and may become in short supply as supplies of crude oil become more difficult to obtain. Attempts to extend these fuels by addition thereto of non-petroleum distillates, such as those derived from shale oil, tar sands, H-oil etc., have been unsatisfactory because the extended fuels have decreased thermal stability as measured by ASTM D 3241 - the JFTOT Test.
It is also known that it is desirable to improve the stability with respect to oxidation at elevated temperatures of other hydrocarbon fuels which may have a thermal stability rating of unsatisfactory or satisfactory.